The "In Vitro Antiviral Screen for Hepadnaviruses" Contract is an endeavor by the Hepatitis Program of the Division of Microbiology and Infectious Diseases, NIAID, to facilitate investigators in their pursuit of identifying agents/compounds capable of ameliorating/curing hepatitis R chronic infection. The goal is to identify drugs to rescue the over 300 million chronic carriers of hepatitis B in the world--one million in the U.S. alone--from the progressive, debilitating illness caused by the virus. As an integral part of DMID's preclinical antiviral drug development, the antiviral screen has already met with a high degree of success. Drugs selected by Program staff for entry to the screening process are evaluated for their ability to inhibit the virus, toxicity to cells, and for some compounds preliminary determination of mechanism-of-action in a tissue culture model. If suitable they are recommended for further in vivo studies in the woodchuck animal model funded by separate NIAID contracts. This contract is a vehicle for screening and selection of compounds generated by university-based investigators and small businesses who do not have such in-house capabilities and expertise.